A network has two paths from Router A to a destination server. Path X uses 2 hops over T1 lines (1.5 Mbps each). Path Y uses 4 hops over gigabit Ethernet links (1 Gbps each). How will RIP route traffic?
AVia Path Y, because RIP weights routes by available bandwidth
BVia Path X, because RIP uses hop count as its only metric and Path X has fewer hops
CVia Path Y, because RIP computes a bandwidth-delay product for each path
DRIP will load-balance across both paths since they are both valid routes
RIP uses hop count as its sole metric, treating every link as cost 1 regardless of bandwidth, latency, or reliability. Path X has 2 hops, Path Y has 4 hops, so RIP selects Path X — even though Path Y offers roughly 667× more bandwidth per link. This is a fundamental limitation of hop-count metrics: they are blind to link quality, leading RIP to frequently choose suboptimal paths in real networks.
Question 2 Multiple Choice
After a link in a RIP network fails, why can it take several minutes for all routers to learn about the failure and converge on new routes?
ARIP routers must synchronize their clocks before exchanging topology information
BRIP sends updates only every 30 seconds, and counting-to-infinity can cause routers to slowly increment a dead route's cost one hop at a time until reaching 16
CRIP requires explicit acknowledgment from every router in the autonomous system before removing a route
DThe default TTL of RIP packets is set equal to the update interval of 30 seconds
RIP's 30-second update timer means bad news travels slowly — a failure may not be propagated for up to 30 seconds per hop. Worse, the count-to-infinity problem causes routers to keep incrementing a failed route's hop count (1, 2, 3 ... 16) rather than immediately marking it unreachable, because each router believes a neighbor still has a valid path. Reaching the maximum hop count of 16 is the only way the route is eventually discarded. Mitigations like split horizon, poison reverse, and triggered updates reduce but do not eliminate this problem.
Question 3 True / False
Split horizon largely solves the count-to-infinity problem, making RIP as fast to converge as link-state protocols like OSPF after a topology change.
TTrue
FFalse
Answer: False
Split horizon prevents a router from advertising a route back to the neighbor it learned it from, which eliminates simple two-router routing loops. However, in networks with three or more routers forming a loop topology, counting-to-infinity can still occur even with split horizon. Additionally, the 30-second update interval itself fundamentally limits convergence speed regardless of loop prevention. OSPF, which uses link-state flooding and Dijkstra's algorithm, converges far more quickly after a failure.
Question 4 True / False
RIPv2 improved on RIPv1 by adding support for classless (CIDR) addressing, including subnet mask information in route advertisements.
TTrue
FFalse
Answer: True
RIPv1 is a classful protocol that assumes routes conform to class A/B/C boundaries and does not include subnet masks in updates. This made it incompatible with variable-length subnet masking (VLSM) and CIDR. RIPv2 fixed this by including a subnet mask field in each route entry, enabling classless routing. RIPv2 also switched from broadcast (255.255.255.255) to multicast (224.0.0.9) delivery, reducing unnecessary processing on non-RIP devices.
Question 5 Short Answer
Explain why hop count is a poor routing metric and describe a specific network scenario where RIP would choose a significantly worse path than a bandwidth-aware routing protocol. What fundamental information is hop count unable to capture?
Think about your answer, then reveal below.
Model answer: Hop count treats every link as identical, assigning a cost of 1 regardless of bandwidth, latency, reliability, or load. It cannot distinguish a 1 Gbps fiber link from a 56 Kbps dial-up connection. A concrete scenario: a path through three gigabit links (3 hops) vs. a path through two dial-up modems (2 hops) — RIP selects the dial-up path because it has fewer hops, even though the gigabit path delivers orders of magnitude more throughput. OSPF avoids this by using link cost inversely proportional to bandwidth, so high-capacity links are strongly preferred. The fundamental limitation is that hop count conflates topological distance (number of routers traversed) with actual transmission quality.